Integrated circuit cell library for multiple patterning

ABSTRACT

A method is disclosed for defining a multiple patterned cell layout for use in an integrated circuit design. A layout is defined for a level of a cell in accordance with a dynamic array architecture so as to include a number of layout features. The number of layout features are linear-shaped and commonly oriented. The layout is split into a number of sub-layouts for the level of the cell. Each of the number of layout features in the layout is allocated to any one of the number of sub-layouts. Also, the layout is split such that each sub-layout is independently fabricatable. The sub-layouts for the level of the cell are stored on a computer readable medium.

CLAIM OF PRIORITY

This application is a continuation application under 35 U.S.C. 120 ofprior U.S. patent application Ser. No. 12/041,584, filed on Mar. 3,2008, which claims priority under 35 U.S.C. 119(e) to U.S. ProvisionalPatent Application No. 60/892,982, filed Mar. 5, 2007. The disclosuresof the above-identified patent applications are incorporated herein byreference in their entirety.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is also related to U.S. patent application Ser. No.11/683,402, filed on Mar. 7, 2007, and entitled “Dynamic ArrayArchitecture.” This application is also related to U.S. patentapplication Ser. No. 12/013,342, filed on Jan. 11, 2008, and entitled“Semiconductor Device with Dynamic Array Section.” This application isalso related to U.S. patent application Ser. No. 12/013,356, filed onJan. 11, 2008, and entitled “Methods for Designing Semiconductor Devicewith Dynamic Array Section.” This application is also related to U.S.patent application Ser. No. 12/013,366, filed on Jan. 11, 2008, andentitled “Methods for Defining Dynamic Array Section with ManufacturingAssurance Halo and Apparatus Implementing the Same.” This application isalso related to U.S. patent application Ser. No. 12/033,807, filed onFeb. 19, 2008, and entitled “Integrated Circuit Cell Library withCell-Level Process Compensation Technique (PCT) Application andAssociated Methods.” The disclosures of the above-identified patentapplications are incorporated herein by reference.

BACKGROUND

In modern semiconductor fabrication, optical lithography is used topattern layout features onto a semiconductor wafer. Currentstep-and-repeat optical lithography systems and step-scan-and-repeatoptical lithography systems use illumination sources with wavelengths of365 nanometers (nm) (Hg Mine), 248 nm (KrF B-X excimer laser), and 193nm (ArF B-X excimer laser). Historically, it has been possible to useillumination wavelengths larger than the layout feature sizes to bepatterned. However, as layout feature sizes continue to decrease withouta corresponding decrease in available illumination wavelength, thedifference between the smallest wavelength and smallest layout featuresize has become too large for successful lithographic rendering of thefeatures. For example, lithographers are having great difficultypatterning 65 nm layout feature sizes with the 193 nm illuminationsource. Moreover, layout feature sizes are expected to continue todecrease from 65 nm to 45 nm, and on to 32 nm.

Lithographers use the following formula from Lord Rayleigh to estimatethe optical system capability: resolution (half-pitch)=k₁ λ/NA, where k₁is a fitting variable roughly corresponding to a process window, λ isthe illumination wavelength, and NA is the numerical aperture of thelithographic system. When the wavelength λ was larger than thehalf-pitch, typical values for k₁ were over 0.50. Because the featuresize has been decreasing by a factor of 0.7 for each technology node,the value of k₁ has been steadily decreasing for each technology node,while the wavelength λ has been constant, and the NA has been increasingby only 1.1 to 1.2 per technology node step. Additionally, for a NAgreater than about 0.93, immersion systems are needed in which waterreplaces air as the medium between the final lens and the photoresist onthe wafer. These immersion systems are expected to support a NA up toabout 1.35, with no clear, cost-effective solution thereafter.

In view of the foregoing, a solution is needed to enable patterning ofnano-scale feature sizes without having to further decrease illuminationwavelength λ and/or further increase numerical aperture NA.

SUMMARY

In one embodiment, a method is disclosed for defining a multiplepatterned cell layout for use in an integrated circuit design. Themethod includes an operation for defining a layout for a level of acell. The layout is defined in accordance with a dynamic arrayarchitecture to include a number of layout features. The number oflayout features are linear-shaped and commonly oriented. The method alsoincludes an operation for splitting the layout into a number ofsub-layouts for the level of the cell, such that each of the number oflayout features in the layout is allocated to any one of the number ofsub-layouts. The layout is split such that each sub-layout isindependently fabricatable. The method further includes an operation forstoring the number of sub-layouts for the level of the cell on acomputer readable medium.

In another embodiment, a method is disclosed for creating a cell libraryfor multiple patterning of a chip layout. The method includes anoperation for defining a cell to include a number of levels having arespective linear layout defined in accordance with a dynamic arrayarchitecture. The dynamic array architecture is defined by layoutfeatures that are linear-shaped and commonly oriented. The cellrepresents an abstraction of a logic function and encapsulateslower-level integrated circuit layouts for implementing the logicfunction. For one or more select levels of the cell, the method includesan operation for splitting the respective linear layout into a number ofsub-layouts, such that each of the number of layout features in therespective linear layout is allocated to any one of the number ofsub-layouts, and such that each sub-layout is independentlyfabricatable. The method further includes an operation for storing adefinition of the cell in a cell library on a computer readable medium.The definition of the cell includes the number of sub-layouts associatedwith each of the select levels of the cell.

In another embodiment, a method is disclosed for designing an integratedcircuit for fabrication. In the method, a plurality of cells are placedtogether on a chip layout to satisfy a netlist of the integratedcircuit. The plurality of cells are selected from a cell library formultiple patterning of the chip layout. Each of the plurality of cellsincludes a common level having a respective linear layout defined inaccordance with a dynamic array architecture. The dynamic arrayarchitecture is defined by layout features that are linear-shaped andcommonly oriented. Each linear layout is split into a number ofsub-layouts, such that each layout feature in each linear layout isallocated to any one of the number of sub-layouts. Layout featuresallocated to a given sub-layout form a consistent pattern within thecommon level of a given cell. The plurality of cells are placed togethersuch that the consistent pattern of layout features, as formed by thegiven sub-layout within the common level, extends in an uninterruptedmanner across the plurality of cells. The extension of the consistentpattern of layout features formed by the given sub-layout across theplurality of cells defines a portion of a chip-wide mask layout for thecommon level. The method also includes an operation for storing thechip-wide mask layout for the common level on a computer readablemedium.

In another embodiment, a set of masks for fabricating a common level ofa semiconductor chip is disclosed. The set of masks includes a firstmask having an area defined in accordance with a dynamic arrayarchitecture to include a first number of linear layout features. Thefirst number of linear layout features are commonly oriented. Also, eachof the first number of linear layout features is devoid of a substantialchange in traversal direction across the first mask. The first number oflinear layout features form a first sub-layout that defines a firstportion of one or more cells. Each of the one or more cells representsan abstraction of a logic function and encapsulates lower-levelintegrated circuit layouts for implementing the logic function. The setof masks also includes a second mask having an area defined inaccordance with the dynamic array architecture to include a secondnumber of linear layout features. The second number of linear layoutfeatures are commonly oriented with the first number of linear layoutfeatures. Also, each of the second number of linear layout features isdevoid of a substantial change in traversal direction across the secondmask. The area of the second mask defined in accordance with the regulararchitecture is to be aligned with the area of the first mask defined inaccordance with the regular architecture. The second number of linearlayout features form a second sub-layout which defines a second portionof the one or more cells.

Other aspects and advantages of the invention will become more apparentfrom the following detailed description, taken in conjunction with theaccompanying drawings, illustrating by way of example the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration showing an exemplary layout for a level of acell defined in accordance with the dynamic array architecture, inaccordance with one embodiment of the present invention;

FIG. 2A is an illustration showing a splitting of the layout of FIG. 1into two sub-layouts, in accordance with one embodiment of the presentinvention;

FIG. 2B is an illustration showing the first sub-layout as defined inthe layout splitting of FIG. 2A, in accordance with one embodiment ofthe present invention;

FIG. 2C is an illustration showing the second sub-layout as defined inthe layout splitting of FIG. 2A, in accordance with one embodiment ofthe present invention;

FIG. 2D is an illustration showing the splitting of the layout of FIG.2A into three sub-layouts, in accordance with one embodiment of thepresent invention;

FIG. 3 is an illustration showing a PCT processed version of thesub-layout of FIG. 2C, in accordance with one embodiment of the presentinvention;

FIGS. 4A-4C are illustrations showing possible sub-layout sequences fora layout that is split into three sub-layouts, in accordance with oneembodiment of the present invention;

FIG. 5A is an illustration showing a gate level layout and metal 2 levellayout for a cell, in accordance with one embodiment of the presentinvention;

FIGS. 5B-5E are illustrations showing different variants of the cell ofFIG. 5A, in accordance with one embodiment of the present invention;

FIG. 5F-5G are illustrations showing placement of cell variants next toeach other such that the sub-layout patterns for multiple levels extendacross the cell boundaries, in accordance with one embodiment of thepresent invention;

FIG. 6A is an illustration showing a non-segmented layout of a level ofa cell, in accordance with one embodiment of the present invention;

FIG. 6B is an illustration showing a first non-segmented sub-layoutincluding the linear-shaped layout features designated by the label A inFIG. 6A, in accordance with one embodiment of the present invention;

FIG. 6C is an illustration showing a second non-segmented sub-layoutincluding the linear-shaped layout features designated by the label B inFIG. 6A, in accordance with one embodiment of the present invention;

FIG. 6D is an illustration showing a layout to be used for cutting thelinear-shaped features as fabricated by the first and secondnon-segmented sub-layouts of FIGS. 6B and 6C, in accordance with oneembodiment of the present invention;

FIG. 6E is an illustration showing the level of the cell following theline cutting by the layout of FIG. 6D, in accordance with one embodimentof the present invention;

FIG. 7 is an illustration showing a flowchart of a method for defining amultiple patterned cell layout for use in an integrated circuit design,in accordance with one embodiment of the present invention;

FIG. 8 is an illustration showing a flowchart of a method for creating acell library for multiple patterning of a chip layout, in accordancewith one embodiment of the present invention; and

FIG. 9 is an illustration showing a flowchart of a method for designingan integrated circuit for fabrication, in accordance with one embodimentof the present invention.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Itwill be apparent, however, to one skilled in the art that the presentinvention may be practiced without some or all of these specificdetails. In other instances, well known process operations have not beendescribed in detail in order not to unnecessarily obscure the presentinvention.

One technique for resolving nano-scale layout features without furtherdecreasing the illumination wavelength and without further increasingthe numerical aperture NA is to utilize multiple patterning. Morespecifically, in multiple patterning, a given layout is split into twoor more sub-layouts that are each exposed separately over the same areaof the chip in the optical lithography process. Although the individualfeature sizes in each of the sub-layouts may be small, i.e., nano-scale,a spacing between adjacent layout features in a given sub-layout issufficiently large to enable resolution of the small layout features.

It should be appreciated that multiple patterning can be quite difficultin traditional random logic patterns and associated cell librariesbecause of their two-dimensionally varying nature, i.e., with layoutfeatures having bends and forks. Additionally, there can be complexissues associated with splitting of two-dimensionally varying patterns,such as phase shifting conflicts. However, use of a cell library definedin accordance with a dynamic array architecture enables straightforwardsplitting of a layout into multiple sub-layouts to be used forlithographic exposure.

A cell, as referenced herein, represents an abstraction of a logicfunction, and encapsulates lower-level integrated circuit layouts forimplementing the logic function. It should be understood that a givenlogic function can be represented by multiple cell variations, whereinthe cell variations may be differentiated by feature size, performance,and process compensation technique (PCT) processing. For example,multiple cell variations for a given logic function may bedifferentiated by power consumption, signal timing, current leakage,chip area, OPC, RET, etc. Additionally, multiple cell variations may bedifferentiated by sub-layout sequence combination, as described herein.It should also be understood that each cell description includes thelayouts for the cell in each level of a chip, as required to implementthe logic function of the cell. More specifically, a cell descriptionincludes layouts for the cell in each level of the chip extending fromthe substrate level up through a particular interconnect level.

The dynamic array architecture represents a semiconductor device designparadigm in which linear-shaped layout features are defined along aregular-spaced virtual grate (or regular-spaced virtual grid) in anumber of levels of a cell, i.e., in a number of levels of asemiconductor chip. The virtual grate is defined by a set of equallyspaced, parallel virtual lines extending across a given level in a givenchip area. The virtual grid is defined by a first set of equally spaced,parallel virtual lines extending across a given level in a given chiparea in a first direction, and by a second set of equally spaced,parallel virtual lines extending across the given level in the givenchip area in a second direction, where the second direction isperpendicular to the first direction. In one embodiment, the virtualgrate of a given level is oriented to be substantially perpendicular tothe virtual grate of an adjacent level. However, in other embodiments,the virtual grate of a given level is oriented to be eitherperpendicular or parallel to the virtual grate of an adjacent level.

In one embodiment, each linear-shaped layout feature of a given level issubstantially centered upon one of the virtual lines of the virtualgrate associated with the given level. A linear-shaped layout feature isconsidered to be substantially centered upon a particular line of avirtual grate when a deviation in alignment between of the centerline ofthe linear-shaped layout feature and the particular line of the virtualgrate is sufficiently small so as to not reduce a manufacturing processwindow from what would be achievable with a true alignment between ofthe centerline of the linear-shaped layout feature and the line of thevirtual grate.

In one embodiment, the above-mentioned manufacturing process window isdefined by a lithographic domain of focus and exposure that yields anacceptable fidelity of the layout feature. In one embodiment, thefidelity of a layout feature is defined by a characteristic dimension ofthe layout feature. Also, it should be understood that the centerline ofa given linear-shaped layout feature is defined as a virtual line thatpasses through the cross-sectional centroid of the linear-shaped layoutfeature at all points along its length, wherein the cross-sectionalcentroid of the linear-shaped layout feature at any given point alongits length is the centroid of its vertical cross-section area at thegiven point.

In another embodiment, some linear-shaped layout features in a givenlevel may not be centered upon a virtual line of the virtual grateassociated with the given level. However, in this embodiment, thelinear-shaped layout features remain parallel to the virtual lines ofthe virtual grate, and hence parallel to the other linear-shaped layoutfeatures in the given level. Therefore, it should be understood that thevarious linear-shaped layout features defined in a layout of a givenlevel are oriented to extend across the given level in a parallelmanner.

Also, in the dynamic array architecture, each linear-shaped layoutfeature is defined to be devoid of a substantial change in directionalong its length. The lack of substantial change in direction of alinear-shaped layout feature is considered relative to the line of thevirtual grate along which the linear-shaped layout feature is defined.In one embodiment, a substantial change in direction of a linear-shapedlayout feature exists when the width of the linear-shaped layout featureat any point thereon changes by more than 50% of the nominal width ofthe linear-shaped layout feature along its entire length. In anotherembodiment, a substantial change in direction of a linear-shaped layoutfeature exists when the width of the linear-shaped layout featurechanges from any first location on the linear-shaped layout feature toany second location on the linear-shaped layout feature by more that 50%of the linear-shaped layout feature width at the first location.Therefore, it should be appreciated that the dynamic array architecturespecifically avoids the use of non-linear-shaped layout features,wherein a non-linear-shaped layout feature includes one or more bendswithin a plane of the associated level.

In the dynamic array architecture, variations in a verticalcross-section shape of an as-fabricated linear-shaped layout feature canbe tolerated to an extent, so long as the variation in the verticalcross-section shape is predictable from a manufacturing perspective anddoes not adversely impact the manufacture of the given linear-shapedlayout feature or its neighboring layout features. In this regard, thevertical cross-section shape corresponds to a cut of the as-fabricatedlinear-shaped layout feature in a plane perpendicular to the centerlineof the linear-shaped layout feature. It should be appreciated thatvariation in the vertical cross-section of an as-fabricatedlinear-shaped layout feature along its length can correspond to avariation in width along its length. Therefore, the dynamic arrayarchitecture also accommodates variation in the width of anas-fabricated linear-shaped layout feature along its length, so long asthe width variation is predictable from a manufacturing perspective anddoes not adversely impact the manufacture of the linear-shaped layoutfeature or its neighboring layout features.

Additionally, different linear-shaped layout features within a givenlevel can be designed to have the same width or different widths. Also,the widths of a number of linear-shaped layout features defined alongadjacent lines of a given virtual grate can be designed such that thenumber of linear-shaped layout features contact each other so as to forma single linear-shaped layout feature having a width equal to the sum ofthe widths of the number of linear-shaped layout features.

Within a given level defined according to the dynamic arrayarchitecture, proximate ends of adjacent, co-aligned linear-shapedlayout features may be separated from each other by a substantiallyuniform gap. More specifically, adjacent ends of linear-shaped layoutfeatures defined along a common line of a virtual grate are separated byan end gap, and such end gaps within the level associated with thevirtual grate may be defined to span a substantially uniform distance.Additionally, in one embodiment, a size of the end gaps is minimizedwithin a manufacturing process capability so as to optimize filling of agiven level with linear-shaped layout features.

Also, in the dynamic array architecture, a level can be defined to haveany number of virtual grate lines occupied by any number oflinear-shaped layout features. In one example, a given level can bedefined such that all lines of its virtual grate are occupied by atleast one linear-shaped layout feature. In another example, a givenlevel can be defined such that some lines of its virtual grate areoccupied by at least one linear-shaped layout feature, and other linesof its virtual grate are vacant, i.e., not occupied by any linear-shapedlayout features. Furthermore, in a given level, any number ofsuccessively adjacent virtual grate lines can be left vacant. Also, theoccupancy versus vacancy of virtual grate lines by linear-shaped layoutfeatures in a given level may be defined according to a pattern orrepeating pattern across the given level.

Additionally, within the dynamic array architecture, vias and contactsare defined to interconnect a number of the linear-shaped layoutfeatures in various levels so as to form a number of functionalelectronic devices, e.g., transistors, and electronic circuits. Layoutfeatures for the vias and contacts can be aligned to virtual grid,wherein a specification of this virtual grid is a function of thespecifications of the virtual grates associated with the various levelsto which the vias and contacts will connect. Thus, a number of thelinear-shaped layout features in various levels form functionalcomponents of an electronic circuit. Additionally, some of thelinear-shaped layout features within various levels may benon-functional with respect to an electronic circuit, but aremanufactured nonetheless so as to reinforce manufacturing of neighboringlinear-shaped layout features. It should be understood that the dynamicarray architecture is defined to enable accurate prediction ofsemiconductor device manufacturability with a high probability.

In view of the foregoing, it should be understood that the dynamic arrayarchitecture is defined by placement of linear-shaped layout features ona regular-spaced grate (or regular-spaced grid) in a number of levels ofa cell, such that the linear-shaped layout features in a given level ofthe cell are oriented to be substantially parallel with each other intheir traversal direction across the cell. Also, in the dynamic arrayarchitecture, prior to PCT processing, each linear-shaped layout featureis defined to be devoid of a substantial change in direction relative toits traversal direction across the cell. Further description of thedynamic array architecture as referenced herein can be found in each ofco-pending U.S. patent application Ser. Nos. 11/683,402; 12/013,342;12/013,356; and 12/013,366, which are incorporated in their entiretyherein by reference.

FIG. 1 is an illustration showing an exemplary layout for a level of acell 101 defined in accordance with the dynamic array architecture, inaccordance with one embodiment of the present invention. A number oflinear-shaped layout features 105 are placed along virtual lines 103 ofa virtual grate associated with the level of the cell 101. The virtualgrate is defined by a pitch 107 representing a perpendicular spacingbetween adjacent virtual lines 103. In this exemplary embodiment, eachof the linear-shaped layout features 105 is defined to have a width 109.It should be understood, however, that in other embodiments variouslinear-shaped layout features in a given level of a cell may be definedto have a number of different widths.

For purposes of description, it should be considered that the pitch 107of the virtual grate, the width 109 of the linear-shaped features 105,and the occupancy of the virtual grate by the linear-shaped layoutfeatures 105, combine such that the layout of the level of the cell 101is outside a fabrication capability of a given semiconductor fabricationprocess. Therefore, to facilitate fabrication of the level of the cell101, the layout can be split into a number of sub-layouts, such thateach of the number of linear-shaped layout features 105 in the layout isallocated to any one of the number of sub-layouts, and such that eachsub-layout is independently fabricatable within the fabricationcapability of the given semiconductor fabrication process.

In one embodiment, a layout including linear-shaped layout featuresdefined in accordance with the dynamic array architecture is split byallocating sidewardly adjacent layout features to different sub-layouts.It should be understood that allocation of sidewardly adjacent layoutfeatures to different sub-layouts can be applied with any number ofsub-layouts. For example, in the case of double patterning in which twosub-layouts are used, every other layout feature in the layout for thelevel of the cell is allocated to a common sub-layout. In this case,identification of every other layout feature is made in accordance witha direction perpendicular to a traversal direction of the layoutfeatures across the cell.

FIG. 2A is an illustration showing a splitting of the layout of FIG. 1into two sub-layouts, in accordance with one embodiment of the presentinvention. Thus, FIG. 2A is an example of double-patterning. A firstsub-layout in FIG. 2A includes the layout features 105A. A secondsub-layout in FIG. 2A includes the layout features 105B. Therefore, thelayout is split such that sidewardly adjacent layout features areallocated to different sub-layouts. More specifically, every othersidewardly adjacent layout feature is allocated to a common sub-layout.Additionally, it should be understood that when multiple linear-shapedlayout features are placed in a co-aligned manner on a common virtualgrate line, e.g., virtual grate line 103, each of the multiplelinear-shaped layout features is allocated to the same sub-layout. Inother words, each layout feature on a given virtual grate line isallocated to the same sub-layout.

FIG. 2B is an illustration showing the first sub-layout as defined inthe layout splitting of FIG. 2A. FIG. 2C is an illustration showing thesecond sub-layout as defined in the layout splitting of FIG. 2A. Itshould be understood that each of the first and second sub-layouts ofFIGS. 2B and 2C are to fabricated separately on the chip. In thesub-layout of FIG. 2B, adjacent linear-shaped layout features 105A areseparated by a distance 111. Similarly, in the sub-layout of FIG. 2C,adjacent linear-shaped layout features 105B are also separated by thedistance 111. If the distance 111 is sufficiently large such that eachof the first and second sub-layouts is independently fabricatable withinthe fabrication capability of a given semiconductor fabrication process,then use of two sub-layouts is adequate. However, if the distance 111 isnot sufficiently large to enable independent fabrication of the firstand second sub-layouts, the layout of FIG. 2A could be split into morethan two sub-layouts.

FIG. 2D is an illustration showing the splitting of the layout of FIG.2A into three sub-layouts. A first sub-layout in FIG. 2D includes thelayout features 105A. A second sub-layout in FIG. 2D includes the layoutfeatures 105B. A third sub-layout in FIG. 2D includes the layoutfeatures 105C. It should be appreciated that the distance 115 betweenadjacent layout features in each of the three sub-layouts of FIG. 2D islarger than the distance 111 in the two sub-layouts of FIGS. 2B and 2C.Therefore, each of the three sub-layouts having the layout featureseparation distance 115 should be more likely to fall within thefabrication capability of a given semiconductor fabrication process, ascompared to the two sub-layouts having the layout feature separationdistance 111. Thus, by splitting the layout of a given level of a cellinto multiple sub-layouts, it is possible to resolve smaller layoutfeature sizes.

It should be understood that a given layout can be split intoessentially any number of sub-layouts, wherein each sub-layout for thegiven level of the cell is to be fabricated separately. Also, in variousembodiments, a layout for a given level of a cell can be split into anumber of sub-layouts based on layout feature function, layout featurelocation, or a combination thereof. In one embodiment, layout featuressharing a common electrical function can be allocated to a commonsub-layout. For example, layout features for active region contacts canbe commonly allocated to one sub-layout, and layout features for gatecontacts can be commonly allocated to another sub-layout. Also, in oneembodiment, layout features for vias can be allocated to sub-layouts inaccordance with alternating rows and/or columns of the virtual grid uponwhich the via layout features are placed.

Once a given layout is split into multiple sub-layouts, each of thesub-layouts can be process compensation technique (PCT) processedseparately, as each of the sub-layouts will be exposed separately duringthe lithography process. As used herein, a process compensationtechnique (PCT) refers to essentially any processing or adjustment of anintegrated circuit (IC) layout for the purpose of improving or ensuringsuccessful fabrication of the features defined by the IC layout.Examples of various PCTs include optical proximity correction (OPC),resolution enhancement techniques (RET), etch proximity compensation,gap fill compensation (e.g., use of dielectric or metal to fill gaps),chemical mechanical planarization (CMP) compensation, among others. Itshould be understood that the term PCT processing, as used herein,refers to any existing or future form of IC layout processing used toimprove or ensure successful fabrication of features defined by the IClayout.

FIG. 3 is an illustration showing a PCT processed version of thesub-layout of FIG. 2C, in accordance with one embodiment of the presentinvention. A number of OPC shapes 117 are placed at various ends of thelinear-shaped layout features 105B as part of the PCT processing of thesub-layout. In performing the PCT processing on a given sub-layout, alithographic buffer region (“litho-buffer” hereafter) 119 is definedaround the cell 101 to simulate a chip environment in which thesub-layout for the level of the cell 101 may be placed and fabricated.Generally speaking, a litho-buffer associated with a given sub-layoutfor a cell level is defined to include a number of features thatsimulate the neighborhood in which the sub-layout for the cell levelwill be placed during fabrication on the chip. The size of thelitho-buffer for a given cell level is defined by the outward extent ofthe litho-buffer from the cell. For example, in FIG. 3, the litho-buffer119 extends outward from the cell 101 to a boundary 121. The size of thelitho-buffer for a given cell level is set such that the litho-buffercovers an area capable of lithographically influencing fabrication ofthe sub-layout in the given cell level.

In one embodiment, a litho-buffer for a cell level defined in accordancewith the dynamic array architecture can be defined by surrounding thecell level with duplicate instantiations of itself. However, in anotherembodiment, the litho-buffer for the cell level defined in accordancewith the dynamic array architecture can be defined in a more generalizedmanner to include a “blanket” of linear features which approximate thosepresent in the cell level. For example, the blanket of linear featurescan be defined to include a number of linear features placed accordingto an extension of the virtual grate/virtual grid utilized within thecell level, and according to an extension of the sub-layout of the celllevel. Additionally, in the dynamic array architecture, it should beappreciated that PCT corrections may be primarily intended to maintainthe line width of each linear-shaped layout feature in critical regions.Therefore, the PCT corrections can be relatively simple, such asone-dimensional corrections similar to those provided by the OPC shapes117 in FIG. 3. Further description of PCT processing of a given level ofa cell can be found in co-pending U.S. patent application Ser. No.12/033,807, which is incorporated in its entirety herein by reference.

For each layout that is split into a number of sub-layouts, a particularsub-layout sequence can be specified. The sub-layout sequence is definedby allocating an edge layout feature of the layout to a particularsub-layout and by allocating sidewardly adjacent layout features,relative to a direction extending across the layout away from the edgelayout feature, according to a fixed ordering of the number ofsub-layouts. Because each sub-layout sequence is based on allocation ofan edge layout feature to a particular sub-layout, the number ofpossible sub-layout sequences is equal to the number of sub-layouts intowhich the layout is split.

FIGS. 4A-4C are illustrations showing possible sub-layout sequences fora layout that is split into three sub-layouts, in accordance with oneembodiment of the present invention. In each of FIGS. 4A-4C, the threesub-layouts are designed by the letters A, B, and C, respectively. Also,in each of FIGS. 4A-4C, the fixed ordering of the number of sub-layoutsis specified as A-B-C. Therefore, FIG. 4A shows a first sub-layoutsequence in which the left edge layout feature 401 is allocated tosub-layout A, and the fixed ordering of sub-layouts (A-B-C) is appliedto sidewardly adjacent features based on the allocation of the left edgelayout feature 401 to sub-layout A. FIG. 4B shows a second sub-layoutsequence in which the left edge layout feature 401 is allocated tosub-layout B, and the fixed ordering of sub-layouts (A-B-C) is appliedto sidewardly adjacent features based on the allocation of the left edgelayout feature 401 to sub-layout B. FIG. 4C shows a third sub-layoutsequence in which the left edge layout feature 401 is allocated tosub-layout C, and the fixed ordering of sub-layouts (A-B-C) is appliedto sidewardly adjacent features based on the allocation of the left edgelayout feature 401 to sub-layout C.

A number of variants of a cell can be generated by specifying differentcombinations of sub-layout sequences across the various levels of thecell. For example, FIG. 5A is an illustration showing a gate levellayout and metal 2 level layout for a cell 501, in accordance with oneembodiment of the present invention. For ease of illustration, gatelevel layout features 503 and metal 2 level layout features 505 areabbreviated in their traversal direction across the cell 501 to avoidobscuring each other. However, it should be understood that each gatelevel feature 503 and each metal 2 level feature 505 extends across thecell 501, as indicated by arrows 507.

In the present example, the gate level layout is split into twosub-layouts. Similarly, the metal 2 level layout is split into twosub-layouts. For ease of description, it is assumed that no other levelsof the cell 501 are split into sub-layouts. FIGS. 5B-5E areillustrations showing different variants of the cell 501. The gate levellayout is split into two sub-layouts identified as 503A and 503B,respectively. The metal 2 level layout is split into two sub-layoutsidentified as 505A and 505B, respectively. Because the gate level layoutis split into two sub-layouts, there are two possible sub-layoutsequences for the gate level, i.e., 503A-503B, and 503B-503A. Also,because the metal 2 level layout is split into two sub-layouts, thereare two possible sub-layout sequences for the metal 2 level layout,i.e., 505A-505B, and 505B-505A. Therefore, in considering thecombination of sub-layout sequences across the levels of the cell 501,four variants of the cell 501 can be generated based on uniquesub-layout sequence combinations.

FIG. 5A shows a cell variant 501A in which the combination of sub-layoutsequences applied across the levels of the cell 501 is defined by503A-503B for the gate level and 505A-505B for the metal 2 level. FIG.5B shows a cell variant 501B in which the combination of sub-layoutsequences applied across the levels of the cell 501 is defined by503B-503A for the gate level and 505A-505B for the metal 2 level. FIG.5C shows a cell variant 501C in which the combination of sub-layoutsequences applied across the levels of the cell 501 is defined by503A-503B for the gate level and 505B-505A for the metal 2 level. FIG.5D shows a cell variant 501D in which the combination of sub-layoutsequences applied across the levels of the cell 501 is defined by503B-503A for the gate level and 505B-505A for the metal 2 level.

Because a chip-wide mask is used to fabricate a conglomeration of cells,a given sub-layout pattern should extend across cell boundaries.Therefore, a cell variant having an appropriate sub-layout sequence ineach level thereof should be placed next to another cell when thechip-wide layout is placed and routed, such that the sub-layout patternfor a given level extends across cell boundaries. For example, FIG. 5Fis an illustration showing placement of cell variant 501B next to cellvariant 501A such that the sub-layout patterns for the gate level andthe metal 2 level extend across the cell boundaries. Also, FIG. 5G is anillustration showing placement of cell variant 501D next to cell variant501C such that the sub-layout patterns for the gate level and the metal2 level extend across the cell boundaries.

The splitting of various layouts of a cell into multiple sub-layouts canbe built into the cell library. Through use of the dynamic arrayarchitecture, it is possible to split a layout of a given cell levelinto multiple sub-layouts as the cell library is being created. Also,each variant of a given cell can be stored in the cell library, whereineach cell variant corresponds to a unique combination of sub-layoutsequences applied across the levels of the given cell. Thus, duringplacing and routing of the chip, appropriate cell variants can beselected from the cell library for placement on the chip to ensure thatchip-level layout patterns are maintained across the chip. In oneembodiment, a router used to place and route the chip is defined tounderstand how the various layouts for each level of the chip are split,thereby enabling placement of cells such that sub-layouts for a givenlevel align and extend across cell boundaries.

In one embodiment, chip-wide layout splitting of a given level isaccomplished by placing appropriate cell variants during the chip placeand route process, without considering the chip-wide layout as a whole.In another embodiment, chip-wide layout splitting of a given level canbe performed following the chip place and route process. It should beappreciated that in this embodiment, definition of the various cells inaccordance with the dynamic array architecture serves to significantlyimprove the ease by which the chip-wide layout can be split. Eachchip-wide sub-layout for a given level is defined on a respective mask.The masks for the various sub-layouts of each level of the chip arestored as layout data files to be sent to the mask fabrication facility.The layout data files can be formatted as GDS II (Graphic Data System)database files, OASIS (Open Artwork System Interchange Standard)database files, or any other type of date file format that can beunderstood by the mask fabrication facility.

In another embodiment, multiple patterning can be used to implement aline cutting technique for segmentation of a layout defined inaccordance with the dynamic array architecture. FIG. 6A is anillustration showing a non-segmented layout of a level of a cell 601, inaccordance with one embodiment of the present invention. In thenon-segmented layout, each linear-shaped layout feature is defined toextend continuously across the layout, including across cell boundaries.The non-segmented layout can be split into a number of sub-layouts. Inthe example of FIG. 6A, the non-segmented layout is split into twosub-layouts designated by labels A and B, respectively. FIG. 6B is anillustration showing a first non-segmented sub-layout including thelinear-shaped layout features designated by the label A. FIG. 6C is anillustration showing a second non-segmented sub-layout including thelinear-shaped layout features designated by the label B. Each of thefirst and second non-segmented sub-layouts are fabricated separately onthe same level of the chip.

FIG. 6D is an illustration showing a layout to be used for cutting thelinear-shaped features as fabricated by the first and secondnon-segmented sub-layouts of FIGS. 6B and 6C. The layout of FIG. 6Dincludes layout features 609-1 and 609-2 for line cutting at the cell601 boundary. Also, layout features 609-3 through 609-6 are provided forsegmentation of linear features within the cell 601. The layout of FIG.6D is defined to cut the linear-shaped features as fabricated by thefirst and second non-segmented sub-layouts of FIGS. 6B and 6C, so as toenable electrical connectivity necessary for the logic function of thecell 601. FIG. 6E is an illustration showing the level of the cell 601following the line cutting by the layout of FIG. 6D.

In one embodiment, a set of masks are generated for fabricating a commonlevel of a semiconductor chip in accordance with the line cuttingtechnique illustrated by FIGS. 6A-6E. The set of masks includes a firstmask having an area defined in accordance with a dynamic arrayarchitecture to include a first number of linear layout features definedto extend continuously across the area of the first mask. The firstnumber of linear layout features are commonly oriented. Also, each ofthe first number of linear layout features is devoid of a substantialchange in traversal direction across the first mask. The first number oflinear layout features form a first sub-layout, wherein the firstsub-layout defines a first portion of one or more cells.

The set of masks also includes a second mask having an area defined inaccordance with the dynamic array architecture to include a secondnumber of linear layout features defined to extend continuously acrossthe area of the second mask. The second number of linear layout featuresare commonly oriented with the first number of linear layout features ofthe first mask. Each of the second number of linear layout features isdevoid of a substantial change in traversal direction across the secondmask. The area of the second mask defined in accordance with the dynamicarray architecture is to be aligned with the area of the first maskdefined in accordance with the dynamic array architecture, therebycausing the second number of linear layout features to be interleavedwith the first number of linear layout features. The second number oflinear layout features form a second sub-layout, wherein the secondsub-layout defines a second portion of the one or more cells.

The set of masks also includes a third mask having an area defined toinclude a third number of linear layout features. The third number oflinear layout features are oriented to be substantially perpendicular toboth the first and second number of linear layout features, when thearea of the third mask is aligned with the areas of the first and secondmasks. The third number of linear layout features are defined to providefor cutting of a portion of the first and second number of linear layoutfeatures, so as to segment the first and second number of linear layoutfeatures to enable electrical connectivity necessary for the logicfunction of each of the one or more cells. It should be understood thatenumeration of the above-mentioned masks as “first,” “second,” and“third” is provided for purposes of mask differentiation and is notintended to convey an absolute number of a given mask.

Also, in another embodiment, the non-segmented layout of FIG. 6A can beformed using a self-aligned double patterning (SADP) process, in lieu ofusing the separate sub-layout masks of FIGS. 6B and 6C. In thisembodiment, the cutting layout, i.e., cut mask, of FIG. 6D can be usedto cut the non-segmented layout features formed using the SADP process,so as to yield the layout shown in FIG. 6E. Also, it should beappreciated that the SADP process in this embodiment can be extended toa self-aligned quadruple patterning (SAQP) process, and beyond.

In one embodiment, multiple patterning, as described herein, isperformed by separately loading different sub-layouts for a given levelinto a stepper. In this embodiment, alignment between the layoutfeatures of the different sub-layouts should be performed accurately toensure proper spacing between layout features in the given level. Inanother embodiment, multiple patterning is performed using a doubleexposure technique in which multiple sub-layouts can be exposed on awafer with a single alignment of the wafer to the scanner opticalcolumn. In one embodiment, the double exposure technique can beperformed with each of multiple sub-layouts on a respective mask. Inanother embodiment, if the chip size allows, the double exposuretechnique can be performed with each of the multiple sub-layouts on thesame mask, with an offset between the sub-layouts.

Moreover, it should be appreciated that use of the dynamic arrayarchitecture assists with alignment of sub-layouts when fabricating agiven level of the chip. For example, in one embodiment, alignment inthe direction along the length of the linear-shaped layout features maybe more relaxed relative to alignment in the perpendicular directionextending between layout features. Also, given the parallelism of thelinear-shaped layout features in a given level, proper rotationalalignment of the sub-layouts for the given level may be more easilyidentified.

FIG. 7 is an illustration showing a flowchart of a method for defining amultiple patterned cell layout for use in an integrated circuit design,in accordance with one embodiment of the present invention. The methodincludes an operation 701 for defining a layout for a level of a cell,wherein the layout is defined in accordance with a dynamic arrayarchitecture to include a number of layout features. The number oflayout features are linear-shaped and commonly oriented. The method alsoincludes an operation 703 for splitting the layout into a number ofsub-layouts for the level of the cell, such that each of the number oflayout features in the layout is allocated to any one of the number ofsub-layouts, and such that each sub-layout is independentlyfabricatable.

In one embodiment, a size of the layout features and a spacing betweenadjacent layout features in the layout for the level of the cell, priorto the splitting of operation 703, are outside a fabrication capabilityof a given semiconductor fabrication process. However, the size of thelayout features and a spacing between adjacent layout features in eachsub-layout for the level of the cell, after the splitting of operation703, are within the fabrication capability of the given semiconductorfabrication process.

In one embodiment, sidewardly adjacent layout features in the layout forthe level of the cell are allocated to different sub-layouts. In oneembodiment, layout features sharing a common electrical function in thelayout for the level of the cell are allocated to a common sub-layout.In one embodiment, layout features for active region contacts arecommonly allocated to one sub-layout, and layout features for gatecontacts are commonly allocated to another sub-layout. In oneembodiment, every other layout feature in the layout for the level ofthe cell is allocated to a common sub-layout, wherein an identificationof every other layout feature is made in accordance with a directionperpendicular to a traversal direction of the layout features across thecell.

The method further includes an operation 705 for storing the number ofsub-layouts for the level of the cell on a computer readable medium. Itshould be understood that each sub-layout for the level of the cell isto be fabricated separately within a common area of a chip.Additionally, operations 701-705 are repeated for a number of levels ofthe cell.

In one embodiment, the method can also include an operation for defininga sub-layout sequence for the level of the cell by allocating an edgelayout feature of the level of the cell to a particular sub-layout, andby allocating sidewardly adjacent layout features (relative to adirection extending across the level of the cell away from the edgelayout feature) according to a fixed ordering of the number ofsub-layouts for the level of the cell. In this embodiment, the methodcan further include an operation for generating a number of variants ofthe cell, wherein each variant of the cell is defined by a uniquecombination of sub-layout sequences applied across levels of the cell.Each variant of the cell can be stored in a cell library on a computerreadable medium.

Additionally, in one embodiment of the method, PCT processing can beperformed on each sub-layout to generate a PCT processed version eachsub-layout. The PCT processed version of each sub-layout can be storedin a cell library on a computer readable medium. In this embodiment, thePCT processing is performed on a given sub-layout by defining alithographic buffer region around the given sub-layout. The lithographicbuffer region is defined to include a number of features that simulate aneighborhood of the given sub-layout around the cell when placed on achip.

FIG. 8 is an illustration showing a flowchart of a method for creating acell library for multiple patterning of a chip layout, in accordancewith one embodiment of the present invention. The method includes anoperation 801 for defining a cell to include a number of levels having arespective linear layout defined in accordance with a dynamic arrayarchitecture. The method also includes an operation 803 in which, forone or more select levels of the cell, the respective linear layout issplit into a number of sub-layouts, such that each of the number oflayout features in the respective linear layout is allocated to any oneof the number of sub-layouts, and such that each sub-layout isindependently fabricatable. The method further includes an operation 805for storing a definition of the cell in a cell library on a computerreadable medium. The definition of the cell includes the number ofsub-layouts associated with each of the select levels of the cell.

In one embodiment, the method of FIG. 8 further includes an operationfor generating a number of variants of the cell. Each variant of thecell is defined by a unique combination of sub-layout sequences appliedacross the select levels of the cell. A sub-layout sequence for a givenlevel of the cell is defined by allocating an edge layout feature of thegiven level of the cell to a particular sub-layout, and by allocatingsidewardly adjacent layout features (relative to a direction extendingacross the given level of the cell away from the edge layout feature)according to a fixed ordering of the number of sub-layouts for the givenlevel of the cell. In this embodiment, each variant of the cell isstored in the cell library on the computer readable medium.

Also, in one embodiment, the method of FIG. 8 can include an operationfor PCT processing each sub-layout to generate a PCT processed versionof each sub-layout. In this embodiment, the PCT processed version ofeach sub-layout is stored in the cell library on the computer readablemedium. Additionally, in one embodiment, prior to being split into thenumber of sub-layouts in operation 803, each linear layout is outside afabrication capability of a given semiconductor fabrication process.However, in this embodiment, after splitting of the linear layout inoperation 803, each of the number of sub-layouts is within thefabrication capability of the given semiconductor fabrication process.

FIG. 9 is an illustration showing a flowchart of a method for designingan integrated circuit for fabrication, in accordance with one embodimentof the present invention. The method includes an operation 901 forplacing a plurality of cells together on a chip layout to satisfy anetlist of the integrated circuit. In operation 901, the plurality ofcells are selected from a cell library for multiple patterning of thechip layout. Each of the plurality of cells includes a common levelhaving a respective linear layout defined in accordance with a dynamicarray architecture. Also, each linear layout is split into a number ofsub-layouts, such that each layout feature in each linear layout isallocated to any one of the number of sub-layouts, and such that layoutfeatures allocated to a given sub-layout form a consistent patternwithin the common level of a given cell.

Also, the plurality of cells are placed together in operation 901 suchthat the consistent pattern of layout features fanned by the givensub-layout within the common level extends in an uninterrupted manneracross the plurality of cells. Moreover, the extension of the consistentpattern of layout features formed by the given sub-layout across theplurality of cells defines a portion of a chip-wide mask layout for thecommon level. Additionally, each sub-layout is defined on a separatechip-wide mask layout for the common level, wherein each chip-wide masklayout is to be independently fabricated in a co-aligned manner on thecommon level. The method further includes an operation 903 for storingthe chip-wide mask layout for the common level on a computer readablemedium.

The invention described herein can be embodied as computer readable codeon a computer readable medium. The computer readable medium is any datastorage device that can store data which can be thereafter be read by acomputer system. Examples of the computer readable medium include harddrives, network attached storage (NAS), read-only memory, random-accessmemory, CD-ROMs, CD-Rs, CD-RWs, magnetic tapes, and other optical andnon-optical data storage devices. The computer readable medium can alsobe distributed over a network coupled computer systems so that thecomputer readable code is stored and executed in a distributed fashion.Additionally, a graphical user interface (GUI) implemented as computerreadable code on a computer readable medium can be developed to providea user interface for performing any embodiment of the present invention.

While this invention has been described in terms of several embodiments,it will be appreciated that those skilled in the art upon reading thepreceding specifications and studying the drawings will realize variousalterations, additions, permutations and equivalents thereof. Therefore,it is intended that the present invention includes all such alterations,additions, permutations, and equivalents as fall within the true spiritand scope of the invention.

What is claimed is:
 1. A semiconductor chip, comprising: a gateelectrode level including a plurality of linear-shaped conductivestructures defined to extend lengthwise in a first direction, theplurality of linear-shaped conductive structures positioned inaccordance with a fixed pitch such that a distance as measured in asecond direction perpendicular to the first direction betweenfirst-direction-oriented-lengthwise-centerlines of any two of theplurality of linear-shaped conductive structures is substantially equalto an integer multiple of the fixed pitch, wherein the plurality oflinear-shaped conductive structures includes a first set oflinear-shaped conductive structures corresponding to a first sub-layoutand a second set of linear-shaped conductive structures corresponding toa second sub-layout, the second set of linear-shaped conductivestructures interleaved with the first set of linear-shaped conductivestructures such that each linear-shaped conductive structure of thesecond set of linear-shaped conductive structures is separated from atleast one adjacently located linear-shaped conductive structure of thefirst set of linear-shaped conductive structures by the fixed pitch asmeasured in the second direction between theirfirst-direction-oriented-lengthwise-centerlines, wherein the first setof linear-shaped conductive structures is manufactured using a firstmask, and wherein the second set of linear-shaped conductive structuresis manufactured using a second mask different from the first mask, andwherein the first set of linear-shaped conductive structures ismanufactured separately from the second set of linear-shaped conductivestructures.
 2. A semiconductor chip as recited in claim 1, wherein theinteger multiple of the fixed pitch is equal to the fixed pitchmultiplied by a whole number selected from a set of whole numbersincluding zero.
 3. A semiconductor chip as recited in claim 2, whereinsome of the plurality of linear-shaped conductive structures aresubstantially co-aligned such that the distance as measured in thesecond direction between theirfirst-direction-oriented-lengthwise-centerlines is substantially equalto zero.
 4. A semiconductor chip as recited in claim 3, wherein eachadjacently positioned pair of the substantially co-aligned ones of theplurality of linear-shaped conductive structures are separated from eachother by a fixed end-to-end spacing as measured in the first direction.5. A semiconductor chip as recited in claim 2, wherein some of the firstset of linear-shaped conductive structures are substantially co-alignedsuch that the distance as measured in the second direction perpendicularto the first direction between theirfirst-direction-oriented-lengthwise-centerlines is substantially equalto zero, wherein each adjacently positioned pair of the substantiallyco-aligned ones of the first set of linear-shaped conductive structuresare separated from each other by a fixed end-to-end spacing as measuredin the first direction, wherein some of the second set of linear-shapedconductive structures are substantially co-aligned such that thedistance as measured in the second direction perpendicular to the firstdirection between their first-direction-oriented-lengthwise-centerlinesis substantially equal to zero, wherein each adjacently positioned pairof the substantially co-aligned ones of the second set of linear-shapedconductive structures are separated from each other by the fixedend-to-end spacing as measured in the first direction.
 6. Asemiconductor chip as recited in claim 5, wherein an adjacentlypositioned pair of the substantially co-aligned ones of the first set oflinear-shaped conductive structures are separated from each other by afirst end-to-end spacing, wherein the adjacently positioned pair of thesubstantially co-aligned ones of the first set of linear-shapedconductive structures have theirfirst-direction-oriented-lengthwise-centerlines positioned on a firstline of extent in the first direction, wherein an adjacently positionedpair of the substantially co-aligned ones of the second set oflinear-shaped conductive structures are separated from each other by asecond end-to-end spacing, wherein the adjacently positioned pair of thesubstantially co-aligned ones of the second set of linear-shapedconductive structures have theirfirst-direction-oriented-lengthwise-centerlines positioned on a secondline of extent in the first direction, wherein the first line of extentin the first direction is separated from the second line of extent inthe first direction by the fixed pitch as measured in the seconddirection.
 7. A semiconductor chip as recited in claim 6, wherein thefirst end-to-end spacing is offset in the first direction from thesecond end-to-end spacing.
 8. A semiconductor chip as recited in claim6, wherein some of the first set of linear-shaped conductive structureshave a first length as measured in the first direction, and wherein acombined length as measured in the first direction of the adjacentlypositioned pair of the substantially co-aligned ones of the first set oflinear-shaped conductive structures is equal to a second length asmeasured in the first direction, and wherein the first end-to-endspacing has a third length as measured in the first direction, wherein asum of the second and third lengths as measured in the first directionis substantially equal to the first length as measured in the firstdirection.
 9. A semiconductor chip as recited in claim 8, wherein someof the second set of linear-shaped conductive structures have a fourthlength as measured in the first direction, and wherein a combined lengthas measured in the first direction of the adjacently positioned pair ofthe substantially co-aligned ones of the second set of linear-shapedconductive structures is equal to a fifth length as measured in thefirst direction, and wherein the second end-to-end spacing has the thirdlength as measured in the first direction, wherein a sum of the fifthand third lengths as measured in the first direction is substantiallyequal to the fourth length as measured in the first direction.
 10. Asemiconductor chip as recited in claim 9, wherein the fourth length asmeasured in the first direction is substantially equal to the firstlength as measured in the first direction.
 11. A semiconductor chip asrecited in claim 10, wherein at least one of the first set oflinear-shaped conductive structures having the first length as measuredin the first direction is positioned between two of the second set oflinear-shaped conductive structures relative to the second direction,each of the two of the second set of linear-shaped conductive structureshaving the fourth length as measured in the first direction.
 12. Asemiconductor chip as recited in claim 1, wherein a spacing between atleast one of the linear-shaped conductive structures of the first set oflinear-shaped conductive structures and an adjacent one of thelinear-shaped conductive structures of the second set of linear-shapedconductive structures is outside a fabrication capability of asemiconductor fabrication process.
 13. A semiconductor chip as recitedin claim 1, wherein the first set of linear-shaped conductive structurescorrespond to a first plurality of linear-shaped conductive structures,and wherein the second set of linear-shaped conductive structurescorrespond to a second plurality of linear-shaped conductive structures,and wherein the fixed pitch of the gate electrode level corresponds to afirst pitch, and wherein the semiconductor chip further comprises afirst interconnect level including a third plurality of linear-shapedconductive structures defined to extend lengthwise in the firstdirection, the third plurality of linear-shaped conductive structurespositioned in accordance with a second pitch such that a distance asmeasured in the second direction perpendicular to the first directionbetween first-direction-oriented-lengthwise-centerlines of any two ofthe third plurality of linear-shaped conductive structures issubstantially equal to an integer multiple of the second pitch, thefirst interconnect level including a fourth plurality of linear-shapedconductive structures defined to extend lengthwise in the firstdirection, the fourth plurality of linear-shaped conductive structurespositioned in accordance with a third pitch such that a distance asmeasured in the second direction perpendicular to the first directionbetween first-direction-oriented-lengthwise-centerlines of any two ofthe fourth plurality of linear-shaped conductive structures issubstantially equal to an integer multiple of the third pitch.
 14. Asemiconductor chip as recited in claim 13, wherein at least one of thesecond and third pitches is equal to the first pitch.
 15. Asemiconductor chip as recited in claim 13, wherein at least one of thesecond and third pitches is equal to the first pitch multiplied by aratio of integers.
 16. A semiconductor chip as recited in claim 1,wherein the plurality of linear-shaped conductive structures includes athird set of linear-shaped conductive structures corresponding to athird sub-layout, the third set of linear-shaped conductive structuresinterleaved with the first and second sets of linear-shaped conductivestructures such that each linear-shaped conductive structure of thethird set of linear-shaped conductive structures is separated from atleast one adjacently located linear-shaped conductive structure of thefirst set of linear-shaped conductive structures by the fixed pitch asmeasured in the second direction between theirfirst-direction-oriented-lengthwise-centerlines, and such that eachlinear-shaped conductive structure of the third set of linear-shapedconductive structures is separated from at least one adjacently locatedlinear-shaped conductive structure of the second set of linear-shapedconductive structures by the fixed pitch as measured in the seconddirection between their first-direction-oriented-lengthwise-centerlines.17. A semiconductor chip as recited in claim 16, wherein the third setof linear-shaped conductive structures is manufactured using a thirdmask different from each of the first mask and the second mask, andwherein the third set of linear-shaped conductive structures ismanufactured separately from both the first and second sets oflinear-shaped conductive structures.
 18. A semiconductor chip as recitedin claim 17, wherein the integer multiple of the fixed pitch is equal tothe fixed pitch multiplied by a whole number selected from a set ofwhole numbers including zero.
 19. A semiconductor chip as recited inclaim 18, wherein some of the plurality of linear-shaped conductivestructures are substantially co-aligned such that the distance asmeasured in the second direction between theirfirst-direction-oriented-lengthwise-centerlines is substantially equalto zero.
 20. A semiconductor chip as recited in claim 19, wherein eachadjacently positioned pair of the substantially co-aligned ones of theplurality of linear-shaped conductive structures are separated from eachother by a fixed end-to-end spacing as measured in the first direction.